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About the sample

This sample is a minimal Game DLL implementation meant to showcase how a game project can be built using only C++ code, as opposed to combining C++ with C# and / or Lua.

The sample implements the following:

  • Animated Entity - Basic entity that with the help of editor properties can play raw animations (Does not use Mannequin!)
  • Environment Probe - Native implementation of an environment probe, normally loaded via Lua in the GameSDK and GameZero projects.
  • Physicalized Entity - Native entity implementation that allows physicalizing a specified model as a rigid or static entity.

The sample does not implement a player using the IActorSystem interface, instead opting for a dummy player entity for the sake of sample simplicity.

Code Breakdown

Startup

Keep in mind that the startup section only covers the Launcher functionality, Editor operates differently via the IEditorGame interface.

 

  1. The Launcher application (see <engine root>/Code/Launcher/WindowsLauncher/ for an example) loads the sample Game DLL and invokes the external 'CreateGameStartup' function.
  2. The sample function CreateGameStartup in <sample root>/Code/Game/GameDll/Main.cpp is invoked and calls CGameStartup::Create, resulting in the CGameStartup instance being created.
  3. The Launcher application calls IGameStartup::Init, which in turn initializes the engine and its modules.
    • This function is responsible for initializing the Game Framework (contained in CryAction.dll), which in turn initializes the engine via the CrySystem module.
  4. The Launcher then calls IGameStartup::Run, invoking the main game loop that runs until the engine is shut down.
    • This function largely delegates the actual process of updating to the IGame implementation inside the game module, which in turn calls IGameFramework::PreUpdate and IGameFramework::PostUpdate in order to start the engine update and render flow.

Entities

Entities in the sample all implement the CNativeEntityBase helper, a class that in turn implements ISimpleExtension and IGameObjectExtension in order to expose a few helper methods for setting and getting Entity properties that can be manipulated via the Sandbox Editor's Properties panel. The sample also implements a custom IEntityPropertyHandler implementation (instantiated once per entity class) in order to provide support for pure C++ entities. Without this, entities need a Lua script in order to expose properties to designers.

Each entity is registered in <sample root>/Code/Game/GameDll/Game/GameFactory.cpp, inside the CGameFactory::Init function. The entity being registered can specify any number of entity properties and then register using CGameFactory::RegisterNativeEntity in order to have the engine recognize and expose the entity to designers.

Dummy Player

The "Player" in this sample is merely a dummy entity automatically spawned at the center of the map in CGameRules::OnClientConnect (called shortly after level load). The entity has no responsibility barring a manual update of the view camera position each frame to match the entity position.

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